A SAS (Serial Attached SCSI) wide link is an input/output interface that connects an HBA (Host Bus Adapter) of a host to a storage device. A SAS wide link is a set of standards that allow a plurality of SASs, each assigned with the same SAS address, to operate as one logical port. A SAS wide link can fall into one of two categories: a static-address assigning type, in which an HBA assigns a SAS address statically; and a wide/narrow type, in which an HBA assigns a SAS address that is available for both a wide link and a narrow link.
FIG. 9A is diagram that illustrates a static-address assigning HBA. As illustrated in FIG. 9A, an HBA mounted on a host assigns a static SAS address A0 to a wide link having four SASs. When an input/output request is sent to a storage device, the host outputs the SAS address A0, which is assigned by the HBA and is an address that is used for identifying the host, to a SAS switch (Expander).
FIG. 9B is diagram that illustrates a wide/narrow HBA. As illustrated in FIG. 9B, when in narrow link mode, an HBA mounted on a host assigns pre-assigned SAS addresses A1 to A4 to four SASs, respectively. When in wide link mode, the HBA mounted on the host assigns any one of the pre-assigned four SAS addresses A1 to A4 that are used in narrow link mode to the wide link. When an input/output request is sent to a storage device, the host outputs the SAS address that is assigned by the HBA to a SAS switch as an address that is used for identifying the host. Depending on the HBA, a SAS address that is assigned by the HBA can be changed as the result of an action, such as the detachment or attachment of a cable.
When a SAS address of an HBA is changed as the result of an action, such as the detachment or attachment of a cable, a problem occurs in that a storage device cannot respond to the changed SAS address. In other words, when a host uses a changed SAS address as an address that is used for identifying the host to send an input/output request to a storage device, the storage device cannot recognize the SAS address.
According to an aspect of the storage device of the present invention, even when an HBA address has been changed as the result of an action, such as the detachment or attachment of a cable, the storage device can still respond to the changed address.